It is well used by desert travellers (5)
I believe the answer is:
oasis
This clue might be a double definition.
'it is well' is the first definition.
(source of water)
'desert travellers' is the second definition.
The answer and definition can be both locations as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'used by' is the link.
Can you help me to learn more?
(Other definitions for oasis that I've seen before include "haven for travellers" , "Feature of desert" , "Peaceful spot" , "Britpop group" , "Green spot; rock group" .)